mGy Range Research Articles

Photoluminescence, scintillation, and TSL properties of Dy-doped BaCaBO3F

We fabricated BaCaBO3F (BCBF) with various Dy concentrations (0.1 %, 1 %, and 5 %), and evaluated the luminescence properties for radiation dosimetry. Sharp scintillation peaks originating from the 4f → 4f transition of Dy3+ were observed. Furthermore, thermally stimulated luminescence (TSL) glow curves were recorded, and a TSL glow peak at approximately 120 °C was observed. The 0.1 % Dy-doped BCBF exhibited the highest TSL intensity, and dose response curves of the 0.1–1 % Dy-doped BCBF were obtained in the 0.1–10000 mGy range. Moreover, at least seven activation energy levels related to TSL were confirmed by the TSL isothermal decay analysis.

Dosimetric properties of Tm2O3-doped Ca2BO3Cl

In this work, we prepared Ca2BO3Cl with various amounts (0.1%–1.0%) of Tm2O3 by conventional solid-state reaction and investigated the dosimeter properties. Scintillation peaks at 370, 455, 470, and 650 nm that were derived from the 4f→4f transition of Tm3+ appeared in the X-ray induced scintillation spectra, and the highest scintillation intensity was detected from the 0.5% Tm2O3-doped Ca2BO3Cl. Furthermore, the Tm2O3-doped Ca2BO3Cl exhibited a thermally-stimulated luminescence (TSL) with a main glow peak at 300 °C, and the fabricated Tm2O3-doped Ca2BO3Cl exhibited a linear response in the 0.1–1000 mGy range. In addition, the TSL spectra confirmed that a final luminescence process for the TSL was the 4f→4f transition of Tm3+. In addition to TSL, optically-stimulated luminescence that was attributable to the 4f→4f transition of Tm3+ was recorded under 520 nm light, and the lowest detectable limit was about 1 mGy.

Advancing dosimetry for Dating Environmental Materials: Development of an ultra-sensitive beta dosimeter system and potential for beta autoradiography

Beta Dose Rate heterogeneity is a recognized source of uncertainty when applying luminescence dating to heterogeneous samples, such as coarse crystalline rocks and clast-rich sediments. Simulations have shown that a combination of a heterogeneous distribution of minerals and radioactive elements can lead to complex dose distributions, overdispersion and potentially to bias in equivalent dose determinations. However setting realistic conditions for such simulations remains difficult, and there are at present only a few experimental validation cases for such simulated systems. Project ADDEM is investigating means of linking Monte Carlo simulations of dose rate to specific minerals with direct observations using high sensitivity phosphor plates and laser scanning imaging systems in combination with phase mapping. To overcome some of the limitations of autoradiographic imaging of low level beta dose distributions work has been undertaken using Landauer alumina OSL phosphor screens in combination with a laser scanning system developed at the Scottish Universities Environmental Research Centre (SUERC). Preliminary excitation spectra, emission band characterization and time resolved measurements were undertaken, confirming the potential to recording low doses using asynchronous stimulation at 635 nm coupled with blue band detection. Taking advantage of the slow decay of the luminescence signal the scanning equipment has been configured for pulsed stimulation and asynchronous detection to maximise signal to background ratios. Exploratory work was calibrated using a 60Co facility capable of calibrating doses in the μGy to mGy range. A series of powdered granulite/basalt mixtures of known mean activity and dose rate (Dr) have also been used to calibrate the phosphor screens. To reduce background levels during autoradiographic signal accumulation rock slices are being exposed in the Zeplin shield of the STFC Boulby Underground Laboratory, in an environment which is essentially free from cosmic ray muon background.Simulations have been conducted providing preliminary deconvolution parameters in order to either reconstruct the beta dose rate (β Dr) distribution received by the grains in the sample, or retrieve the radioactive element distributions in the minerals of the sample, providing the data required for representative simulations of β Dr.This paper outlines the spectroscopy and sensitivity verification of the autoradiography system, confirming its prospects for measuring spatially resolved β Dr distributions with single pixel lower detection limit of 130 μGy and spatial resolution of 150 μm. Prospects are outlined.

Thermoluminescent Characteristics of GR-200, TLD-700H and TLD-100 for Low Dose Measurement: Linearity, Repeatability, Dose Rate and Photon Energy Dependence.

Background: The dose values obtained from procedures of diagnostic radiology are relatively low. To accurately and precisely measure the dose values in this dose range, it is necessary to know the characteristics of dosimeters.Objective: The aim of this study was to evaluate several thermoluminescent characteristics of GR-200, TLD-700H and TLD-100 for low dose measurement.Material and Methods: In this experimental study, linearity, repeatability, dose rate and photon energy dependence of different TLD materials were investigated in a 0.05-10 mGy range dose. It is noteworthy that the data obtained from TLD-100 were considered as reference and the data obtained from two other types of TLDs were compared with them.Results: For all three types of TLD materials, there are linear relations between absorbed dose values to TLDs and their responses. TLD-100 and TLD-700H have very low sensitivity than GR-200. For GR-200 and TLD-100, the coefficients of variation values (%) are 3.00% and 2.01%, respectively, that these values are within the tolerance limit (<7.5%). However, this value for TLD-700H is 10.85% which it is more than the reported tolerance limit. Furthermore, remarkable effects of dose rate and photon energy dependence on the responses of GR-200 are not observed in a 0.5-4 mGy dose range; nevertheless, remarkable effects of dose rate and photon energy dependence on the responses of TLD-100 and TLD-700H are found in this dose range.Conclusion: The evaluated thermoluminescent characteristics for GR-200 are better than two other types of TLDs (TLD-100 and TLD-700H) for low dose values.

Selection of radiation tolerant commercial greases for high-radiation areas at CERN: Methodology and applications

At the European Laboratory for Particle Physics (CERN), commercial greases and oils are extensively used to lubricate moving devices operating in high-radiation areas, absorbing doses up to the MGy range. Due to their sensitivity to radiation, lubricants can become fluid or solid in operation, potentially causing component failures and compromising the operation of the accelerator complex. CERN is therefore developing methodologies to select radiation tolerant commercial lubricants for critical Beam Intercepting Devices (BIDs) such as high-power targets, dumps and collimators. A careful selection of greases is fundamental to reduce the risk of failure, to optimize equipment lifetime and to minimize maintenance and unwanted radiation exposure of personnel in high radiation areas. Three different parameters are considered to select commercial lubricants: the expected total dose absorbed in operation, the maintenance feasibility and the failure impact in terms of accelerator downtime and of personnel involvement in replacement procedures. Based on these criteria, an example of relevant application is presented: the lubrication of the new internal beam dump of the Super Proton Synchrotron (SPS). Experimental radiation damage data allowed the identification of two radiation tolerant commercial greases to lubricate the dump support jack assembly.

Distributed fiber optic radiation sensors

Abstract. The international research efforts focused on the development of radiation sensors based on optic fibers have their origins in the 1970s (Evans et al., 1978). Generally, the lightweight fiber optic sensors are immune to electromagnetic field interference and high voltages making them deployable in harsh environments at hard to reach areas where conventional sensors usually will not work at all. A further advantage of such radiation sensors is the possibility of remote and real-time monitoring (Huston et al., 2001). In this work, we present our results achieved in several research activities for development of fiber optic dosimeters. The findings show that both the measurement of the radiation-induced attenuation (RIA) along the entire sensing fiber and the accompanying change in the refractive index of the fiber core can be used for distributed radiation monitoring in the kGy and MGy range, respectively. Depending on the fiber type and material the RIA shows varying response to dose rates, environmental temperatures and the wavelength of the laser source used. Thereby, an operation with visible laser light provides most favorable performance in terms of high radiation sensitivity. Operating at these wavelengths, RIA monitoring could yield high-sensitivity dose measurement with sub-gray resolution and accuracy (Stajanca and Krebber, 2017b); however, conventional optical time-domain reflectometry (OTDR) systems for RIA measurements operating in the visible range suffer from low-spatial resolution, long measurement times and poor signal-to-noise (SNR) ratio. The limitations of the OTDR performance can be overcome by the incoherent optical frequency domain reflectometry (I-OFDR) developed by the Federal Institute of Materials Research and Testing (BAM, Liehr et al., 2009) with potential for dynamic real-time measurement. Over the years, several highly radiation sensitive fibers, such as perfluorinated polymer optical fibers (PF-POF, Stajanca and Krebber, 2017a), phosphorous-doped silica optical fibers (SOF, Paul et al., 2009), aluminium-doped SOF (Faustov et al., 2013) and erbium-doped SOF (Wosniok et al., 2016) have been identified and are commercially available. As mentioned before, the radiation-induced RIA increase is associated with an increase in the refractive index leading also to material compaction in the fiber core. The latter two effects can be used for measuring radiation distribution based on Brillouin scattering in the range of high radiation doses of several MGy (Phéron et al., 2012; Wosniok et al., 2016). When using fiber optic sensors for radiation monitoring, the existing post-irradiation annealing behavior of the optical fiber sensors must also be considered.

Dosimetric Evaluation in Micro-CT Studies Used in Preclinical Molecular Imaging

In microCT imaging, there is a close relationship between the dose of radiation absorbed by animals and the image quality, or spatial resolution. Although the radiation levels used in these systems are generally non-lethal, they can induce cellular or molecular alterations that affect the experimental results. Here, we describe a dosimetric characterization of the different image acquisition modalities used by the microCT unit of the Albira microPET/SPECT/CT scanner, which is a widely used multimodal imaging system in preclinical research. The imparted dose at the animal surface (IDS) was estimated based on Boone’s polynomial interpolation method and experimental measurements using an ionization chamber and thermoluminescent dosimeters. The results indicated that the imparted dose at surface level delivered to the mice was in the 30 to 300 mGy range. For any combination of current (0.2 or 0.4 mA) and voltage (35 or 45 kV), in the Standard, Good, and Best image acquisition modalities, the dose imparted at surface level in rodents was below its threshold of deterministic effects (250 mGy); however, the High Res modality was above that threshold.

Perioperative Anomalous Pulmonary Venous Return Evaluation With Low-Dose Cardiac Computed Tomography.

Low-dose multidetector computed tomographic angiography (MDCTA) is playing an increasingly larger role in the diagnosis of anomalous pulmonary venous return (APVR). Despite advances in new computed tomographic (CT) techniques with radiation dose reduction, there are limited studies describing radiation dose parameters to allow routine use of cardiac CT in infants and children with APVR. This study compares cardiac CT findings with intraoperative findings and describes comprehensive radiation exposure parameters. A retrospective analysis of 27 patients compared MDCTA and intraoperative or cardiac catheterization findings of the pulmonary venous anatomy. A total of 32 MDCTA studies were performed on these 27 patients. Of the 28 studies with subsequent intervention, MDCTA accurately diagnosed the anomalous pulmonary venous anatomy in 27 (96.4%) patients. Narrowing of the pulmonary venous confluence entrance to the coronary sinus was missed on cardiac CT in one patient due to motion artifact, but it was noted intraoperatively. Median estimated effective radiation dose was 0.98 mSv (range: 0.39-3.2 mSv), and mean estimated effective radiation dose was 1.1 ± 0.68 mSv. Median total dose length product (DLP) was 25 mGy cm (range: 10-83 mGy cm), and mean total DLP was 28 ± 18 mGy cm. Median CTDI volume was 3.8 mGy (range: 2.5-14.6 mGy), and mean CTDI volume was 5.0 ± 3.2 mGy. We conclude that modern cardiac MDCTA is the best imaging modality to guide management in both preintervention and postintervention APVR patients. In this study, we describe comprehensive radiation exposure parameters in infants and children with APVR.

Very low-dose computerized tomography for confirmation of urinary stone presence.

To determine whether a modified non-contrast very low-dose computed tomography (VLD-CT) protocol is applicable for confirmation of known urolithiasis. Consecutive adult patients with a CT scan showing urinary tract stone(s) between 6/2017-12/2018 were included. They were referred to a modified VLD-CT protocol if stone presence was equivocal or if stone location needed reassessment before an endourological interventional procedure. The scanned area was limited to the level of initial stone location caudally. Data on patients' demographics andbody mass index, were collected. The scanned length and radiation dose were calculated. Images were reviewed by two radiologists who assessed stone size and location. Follow-up reference standard included stone passage, surgical removal, and other imaging and clinical information. Sixty-three patients [63 stones, mean BMI 28.7 (range 19-41.9)] were included. VLD-CTs revealed 31 stones in 31 patients, with a mean stone length of 5.5mm. Fifteen stones remained at the same location, and 16 had migrated, of which two appeared in the bladder. Thirty-two stones were not observed on VLD-CT. The mean span scanned on the VLD-CT was 274mm (± 80). The average radiation exposure was 1.47mGy (range 1.09-3.3), and the absorbed dose was 0.77mSv (range 0.39-1.43), compared to 10.24mGy (range 1.75-28.9) and 7.87mSv (range 1.44-18.5) in the previous scan. The mean radiation dose reduction between scans was 89%. On follow-up, all VLD-CT findings were confirmed. A modified imaging protocol is applicable for confirmation of stone presence and location by utilizing very low-dose radiation exposure.

Gamma-radiation effects on luminescence properties of Eu3+ activated LaPO4 phosphor

Abstract Eu3+ activated LaPO4 phosphors were prepared by a high-temperature solid-state method and irradiated to different high-doses gamma-radiation in the 0–4 MGy range. No effects of high-doses of high-energy radiation on phosphor’s morphology and structure were observed, as documented by electron microscopy and X-ray diffraction measurements. On the other hand, photoluminescence measurements showed that emission properties of phosphor were affected by gamma-radiation; changes in radiative properties being prominent for absorbed radiation doses up to 250 kGy after which no additional changes are observed. Judd-Ofelt analysis of emission spectra is performed to thoroughly investigate radiative properties of phosphors. Analysis showed that radiative transition probability of Eu3+ emission decreases while non-radiative probability increases upon gamma-irradiation. Quantum efficiency of emission is decreased from about 46% to 35% when Eu3+ doped LaPO4 powders are exposed to gamma-radiation of 250 kGy dose, showing no additional decrease for higher gamma-radiation doses.

The CGL1 (HeLa × Normal Skin Fibroblast) Human Hybrid Cell Line: A History of Ionizing Radiation Induced Effects on Neoplastic Transformation and Novel Future Directions in SNOLAB.

Cellular transformation assays have been utilized for many years as powerful in vitro methods for examining neoplastic transformation potential/frequency and mechanisms of carcinogenesis for both chemical and radiological carcinogens. These mouse and human cell based assays are labor intensive but do provide quantitative information on the numbers of neoplastically transformed foci produced after carcinogenic exposure and potential molecular mechanisms involved. Several mouse and human cell systems have been generated to undertake these studies, and they vary in experimental length and endpoint assessment. The CGL1 human cell hybrid neoplastic model is a non-tumorigenic pre-neoplastic cell that was derived from the fusion of HeLa cervical cancer cells and a normal human skin fibroblast. It has been utilized for the several decades to study the carcinogenic/neoplastic transformation potential of a variety of ionizing radiation doses, dose rates and radiation types, including UV, X ray, gamma ray, neutrons, protons and alpha particles. It is unique in that the CGL1 assay has a relatively short assay time of 18-21 days, and rather than relying on morphological endpoints to detect neoplastic transformation utilizes a simple staining method that detects the tumorigenic marker alkaline phosphatase on the neoplastically transformed cells cell surface. In addition to being of human origin, the CGL1 assay is able to detect and quantify the carcinogenic potential of very low doses of ionizing radiation (in the mGy range), and utilizes a neoplastic endpoint (re-expression of alkaline phosphatase) that can be detected on both viable and paraformaldehyde fixed cells. In this article, we review the history of the CGL1 neoplastic transformation model system from its initial development through the wide variety of studies examining the effects of all types of ionizing radiation on neoplastic transformation. In addition, we discuss the potential of the CGL1 model system to investigate the effects of near zero background radiation levels available within the radiation biology lab we have established in SNOLAB.

Patient Dose in Fluoroscopically Guided Cervical Discectomy and Fusion.

Cervical discectomy and fusion (CDF) is a minimally invasive procedure, where the accurate placement of the implants is accomplished using fluoroscopic guidance. Therefore, the evaluation of the radiation dose becomes mandatory. The purpose of the current study was to assess patient dose during fluoroscopically guided anterior and/or posterior CDF procedures. Thirty-three patients undergoing single or multiple-level CDF were studied using a mobile C-arm system. Data regarding fluoroscopy time (FT), air kerma area product (KAP) and cumulative dose (CD) were recorded. Patient entrance surface dose (ESD), thyroid absorbed dose and effective dose (ED) were calculated from KAP measurements, utilizing the CALDoseX software. The average FT was 0.12 min (range 0.02-0.48 min), resulting to a KAP value of 0.21 Gy cm2 (range 0.01-1.46 Gy cm2) and a CD value of 0.96 mGy (range 0.04-6.58 mGy). The ESD ranged between 0.08 and 13.58 mGy (average 1.95 mGy), the ED between 0.001 and 0.097 mSv (average 0.015 mSv), while the dose absorbed by the thyroid ranged between 0.01 and 1.12 mGy (average 0.194 mGy). The dose associated with the CDF procedure is very low, comparable to that delivered by a lateral X-ray radiograph of the cervical spine. However, higher doses can be revealed, due to the non-optimum use of the X-ray system and extended FTs, mainly affected by complex clinical conditions, as well as the experience of the neurosurgeon. Additional studies need to be conducted for further investigation of the patient dose from the CDF procedure.

Accuracy and evaluation of irradiation of novel localization devices with unique three-dimensional structures in microendoscopic spine surgery.

Although many reports are available on using a variety of instruments and techniques to prevent wrong-level spine surgery, the accurate localization of the correct spinal level remains problematic. At the same time, surgeons are also required to reduce radiation exposure to patients and operating room personnel. To solve these problems, we developed and used specially designed marking devices with a unique three-dimensional structure. To evaluate the accuracy of our novel devices for localization of the spinal level to prevent wrong-level surgery and reduce the amount and time of radiation exposure during surgery. This was a retrospective cohort study. In 8240 consecutive patients who underwent microendoscopic spine surgery between 1993 and 2012, the incidence of wrong-level surgery was studied. In addition, the amount of radiation exposure and total fluoroscopy time were measured in recent 100 consecutive patients using a digital dosimeter attached to the fluoroscope. Eight (0.097%) patients had undergone wrong-level surgery. The average radiation exposure was 0.26mGy (range 0.10-1.15mGy), and the average total fluoroscopy time was 3.1s (range 1-7s). Our novel localization devices and technique for their use in spine surgery are reliable and accurate for identifying the target level and contributed to reductions in preoperative localization error and radiation exposure to patients and operating room personnel.

Characterization of optically stimulated luminescence for assessment of breast doses in mammography screening

Landauer optically stimulated luminescence (OSL) technology nanoDot dosimeters (OSLDs) are characterized for use in mammography screening at various tube voltages, mAs values and target/filter combinations. The average glandular dose (AGD) for a 50-mm breast, based on the representative compressed breast thickness of a 45-mm polymethyl methacrylate (PMMA) phantom, is assessed using OSLDs with different beam conditions. Further, the linearity of the OSLD response is measured and angular dependence tests are performed for various tube potentials, mAs and target/filter combinations. The breast-absorbed doses are measured at various depths for a 32-kVp X-ray beam at 100 mAs, with a Mo/Rh target/filter combination. The measured incident air kerma values at different lateral positions exhibit a maximum deviation of 6%, and the average relative response of the OSLDs at the reference point (center) with respect to various lateral positions is found to be 1.001 ± 0.09%. The calculated AGD values are in the 1.3 ± 0.1−3.5 ± 0.2 mGy range, depending on the tube potential, tube loading and target/filter combinations. An exposure setup featuring the auto-exposure control (AEC) mode, 28 kVp, 73.8 mAs, and a Mo/Rh target/filter combination may be preferred for mammography screening for a compressed breast thickness of 45 mm.

Multi-MGy Radiation Hard CMOS Image Sensor: Design, Characterization and X/Gamma Rays Total Ionizing Dose Tests

A Radiation Hard CMOS Active Pixel Image Sensor has been designed, manufactured and exposed to X and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{60}{\rm Co}\,\, \gamma $</tex></formula> -ray sources up to several MGy of Total Ionizing Dose (TID). It is demonstrated that a Radiation-Hardened-By-Design (RHBD) CMOS Image Sensor (CIS) can still provide useful images after <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$10~\hbox{MGy}({\rm SiO}_2)$</tex></formula> (i.e. 1 Grad). This paper also presents the first detailed characterizations of CIS opto-electrical performances (i.e. dark current, quantum efficiency, gain, noise, transfer functions, etc.) in the MGy range. These results show that it is possible to design a CIS with good performances even after having absorbed several MGy. Four different RHBD photodiode designs are compared: a standard photodiode design, two well known RHBD layouts and a proposed improvement of the gated photodiode design. The proposed layout exhibits the best performances over the entire studied TID range and further optimizations are discussed. Several original MGy radiation effects are presented and discussed at the device and circuit levels and mitigation techniques are proposed to improve further the radiation hardness of future Rad-Hard CIS developments for extreme TID applications (e.g. for nuclear power plant monitoring/dismantling, experimental reactors (e.g. ITER) or next generation particle physics experiments (e.g. CERN)).

Long-Term Neuropsychological and Cardiac Follow-Up of Children and Adults Who Were Antenatal Exposed to Radiotherapy

ABSTRACT Aim: The use of radiation in medical diagnostics and treatment is standard of care. Apart from deductions from atom bomb and nuclear plant disaster survivors, there are scarce data on the long-term outcome after antenatal exposure to medical radiation. We aimed to assess the general health, cardiac and neuropsychological outcome of children in utero exposed to radiotherapy. Methods: Women treated with radiotherapy during pregnancy were retro- and prospectively registered by the International Network on Cancer, Infertility and Pregnancy (INCIP). Children were assessed at 1.5, 3.0, 6.0 or 9.0 years of age, by echocardiography, a clinical neurological examination, cognitive tests and questionnaires regarding health and behavior. Adults were examined by echocardiography and questionnaires regarding health and behavior. Echocardiographic data were compared to an age- and gender-matched control group and neurocognitive data to test specific age-appropriate norms. Results: Sixteen children (median age: 6.0 years, range 1.5–9.6) and ten adults (median age: 33.0 years, range 22.0–49.0) antenatal exposed to radiotherapy from Belgium, The Netherlands and Italy were enrolled. Median maternal and estimated fetal irradiation were 48 Gy (range, 12–70) and 91 mGy (range, 0–1690), respectively. Conventional and advanced cardiac function measurements were normal. Overall neuropsychological, behavioral and general health outcomes were within normal ranges. No linear relationship was found between fetal dose of radiation and cognitive outcome. One child revealed a severe cognitive delay, however this child was exposed to a relatively low dose of radiotherapy (34 mGy) in addition to other confounding pregnancy complications. The mother suffered from an aggressive non-hodgkin tumor of the brain with impact on her general state (maternal somnolence, hemiplegia and intravenous nutrition) followed by preterm delivery. Conclusions: The overall long-term cardiac, neuropsychological, behavioral and general health outcomes after prenatal exposure to radiotherapy appear to be within normal ranges. Larger series are needed to strengthen these findings. Disclosure: All authors have declared no conflicts of interest.

Dosimetry study of diagnostic X-ray using doped iodide normoxic polymer gels

In radiotherapy, polymer gel dosimeters are used for three-dimensional (3D) dose distribution. However, the doses are within the Gy range. In this study, we attempted to develop a low-dose 3D dosimeter within the mGy range for diagnostic radiology. The effect of the iodinated compound was used as a dose enhancement sensitizer to enhance the dose sensitivity of normoxic polymer gel dosimeters. This study aims to use N-isopropylacrylamide(NIPAM)-based and methacrylic acid (MAGAT)-based gels to evaluate the potential dose enhancement sensitizer, as well as to compare two gels that may be suitable for measuring diagnostic radiation doses. The suitable formulation of NIPAM gel [5% (w/w) gelatin, 5% (w/w) NIPAM, 3% (w/w) N,N′-methylenebisacrylamide (BIS), 5mM tetrakis (hydroxymethyl) phosphonium chloride (THPC), and 87% (w/w) deionized distilled water] and MAGAT gel (4% MAA, 9% gelatin, 87% deionized water, and 10mM THPC) were used and loaded with clinical iodinated contrast medium agent (Iobitridol, Xenetix® 350). Irradiation was conducted using X-ray computed tomography. The irradiation doses ranged from 0mGy to 80mGy. Optical computed tomography was the employed gel measurement system. The results indicate that the iodinated contrast agent yields a quantifiable dose enhancement ratio. The dose enhancement ratios of NIPAM and MAGAT gels are 3.35±0.6 and 1.36±0.3, respectively. The developed NIPAM gel in this study could be suitable for measuring diagnostic radiation doses.

Does the magnetic-guided intramedullary nailing technique shorten operation time and radiation exposure?

The aim of this study is to show whether a new magnetic-guided locking technique is superior to a standard freehand technique in terms of operation time and radiation exposure. This treatment will be used for distal locking of the tibia during intramedullary nailing. This randomized trial is done through 80 patients having tibial fractures with a mean age of 25 years (range 16-67 years). In the magnetic locking group, there were 20 fractures of the distal third, 16 of the shaft, and 4 of the proximal tibia; in the freehand group, these numbers were 15, 20, and 5, respectively. The parameters like operation time, distal locking time, radiation exposure duration, and dose were compared. We placed 100 distal locking screws in the magnetic locking group and 95 in the freehand group. Fluoroscopy was necessary only in the freehand group. All screws were correctly positioned the first time in both groups. The magnetic locking group had a shorter mean surgical time (52 ± 6.2 vs 70 ± 10.9 min; P < 0.01), a shorter mean distal locking time (5 ± 1.1 vs 16 ± 2.0 min; P < 0.01), and a shorter mean placement time for each screw (2 ± 0.5 vs 7 ± 1.2 min; P < 0.01). The magnetic locking group had lower mean radiation exposures (8 ± 4.5 vs 40 ± 7.6 s; P < 0.01) and mean radiation exposure (5.4 ± 2.5 vs 25 ± 6.8 mGy range; P < 0.01). For distal locking during tibial intramedullary nailing, the magnetic locking system is as accurate as the standard freehand technique, but it has lower operative times and radiation exposures compared to the standard freehand technique. Therefore, the magnetic locking system should be preferred to current standard freehand techniques.

Abstract 277: Quality Initiative to Reduce Radiation Exposure and Detect Radiation Injury in the Congenital Cardiac Catheterization Lab

Background: The frequency and duration of cardiac catheterization for patients with complex congenital heart disease have increased as a result of the advances in technique and devices available. Increasing catheter interventions require efforts to reduce patient radiation exposure and improve detection of radiation burns. Follow-up protocols based on fluoroscopy time alone are often inadequate as surveillance measures to identify patients that develop radiation burns. Objective: The objective of this study was (1) to reduce the radiation exposure during cardiac catheterization and (2) to improve the quality of post cardiac catheterization radiation surveillance by the development of standardized dose dependent follow-up protocols. Methods: Quality initiatives introduced to reduce radiation exposure from July 2008 - July 2010 included (1) fluoroscopy frame rate reduction from 30 to 15 fps; (2) digital acquisition frame rate reduction from 30 to 15 fps for pts &gt; 65kg; (3) Toshiba system upgrade superior noise reduction filter with high-quality fluoro-record capabilities. Quality initiatives for follow-up surveillance based on radiation exposure included (1) all patients exposed to a dose of ≥ 3000mGy received a letter explaining radiation risks and possible signs of radiation burns, as well as a phone call 1 week post procedure inquiring about possible signs of radiation burns or other skin changes; (2) all patients exposed to a dose of ≥ 6000mGy received 2 additional phone calls at 3 and 6 weeks post procedure; and (3) all patients exposed to a dose of &gt; 9000mGy had a follow-up appointment with a cardiologist 4-6 weeks post procedure with skin assessment for radiation injury. Results: In 2008, there were 519 patients; median radiation exposure was 544 mGy (range 10-31519); median fluoroscopy time was 23 min (range 1-335); radiation burns N=4. In 2009, there were 495 patients; median radiation exposure was 439 mGy (range 0.4-15955); median fluoroscopy time was 24 min (range 0.1-192); radiation burns N=7. In 2010, there were 519 patients; median radiation exposure was 322 mGy (range 1.6-19196); median fluoroscopy time was 24 min (range 0.5-386); radiation burns N=4. In 2011, there were 572 patients; median radiation exposure was 220 mGy (range 1-11108); median fluoroscopy time was 23 min (range 0.3-201); radiation burns N=3. The median patient radiation exposure decreased by over 50% from 2008 to 2011 (p&lt;0.001 ). Fluoroscopy times did not change significantly during the study period (p=0.9). Conclusions: Quality improvement initiatives aimed at reduction of cardiac catheterization radiation exposure and dose dependent follow-up protocols have been effective in reducing the radiation exposure and improving detection of radiation burns in patients with congenital heart disease undergoing cardiac catheterization.

Neuroembolization may expose patients to radiation doses previously linked to tumor induction

Epidemiological studies indicate a link between low-dose irradiation (<10,000 mGy) to the head and the local occurrence of tumors after decades of delay. Comparable radiation doses can be reached during neuro-endovascular procedures (NEP), but the incidence of similar exposures has not been completely delineated. We compared the levels of radiation to the head measured during NEP to those reported for patients developing radiation-induced cancers. In our prospective study we determined the cumulative maximum entrance skin doses (MESD) and the incidence of epilation in 107 consecutive patients submitted to NEP between 2003 and 2007. We also extensively searched the literature and compared our results with the data we found. The cumulative MESD due to NEP was above 3,000 mGy (range 3,101-5,421 mGy) in 18 patients. In 22 we observed partial epilation within 10 weeks from the initial NEP. Sixty cases of epilation after NEP have been previously reported in the literature. The average of the reported MESD was 4,241 mGy (range 2,000-6,640 mGy). Physical dosimetry and the incidence of partial epilation indicate that about one fifth of the patients submitted to NEP received radiation doses comparable to those linked to the occurrence of tumors. The potential risks of developing tumors after a long delay, when compared to the immediate benefits of endovascular treatment of aneurysm and arteriovenous malformations (AVM) of the brain, do not counterindicate NEP, but increased awareness of the risk should help physicians and patients to make a fully informed decision when other treatments are available.